The demand of wireless data traffic is explosively increasing. To meet such demand, the cellular systems are evolving into multi-tier networks that include base stations with diverse sizes, types, use cases, and so forth. Momentum is increasing to include more multi-tier base stations, such as femtocells, picocells, relay, and the like, in the wireless communications system. Small-sized low-power base stations, such as picocell, femtocell, and the like, become heated topics, because of their potential advantages of low cost, offloading the traffic from macrocells, providing large amount of wireless data traffic to mobile stations, and the like.
Femtocell devices are small base stations designed for small range use, such as home or small business use. Femtocell devices operate in a small range and are designed to provide cellular coverage in small areas such as the home or office. The typical femtocell device connects to a Security Gateway or Softswitch over an Internet Protocol (IP) connection, such as a Digital Subscriber Line (DSL) or broadband cable connection. The Security Gateway or Softswitch is intended to plug into the DSL or cable modem using a standard Ethernet cable.
Femto Base Stations (FBSs) can be open or closed. An open FBS accepts any compatible mobile device (e.g., accepts communications to and from any compatible cell phone, PDA, and the like). A closed FBS requires that the mobile device be authorized to access through the FBS.